Chimp Viruses for Human Vaccines

Human adenoviruses have been proposed as vectors for antigens in vaccines because of their ability to induce strong immune responses in animal models. But there is one major problem—patients that have already been exposed to such adenoviruses naturally develop antibodies against them, which then neutralize the vaccine before it has a chance to deliver its package.

“The body has mounted an immune response, which stays for the rest of its life,” explained Alfredo Nicosia of Okairos in Rome, Italy.

Now, Nicosia and his colleagues believe they have found a solution—use chimpanzee adenoviruses instead. According to their report, out today (January 4) in Science Translational Medicine, chimp adenoviruses avoid the problem of preexisting immunity that can dampen vaccine potency. A second accompanying paper reports the successful clinical trial results for one such chimp virus-based vaccine for hepatitis C.

“The preexisting immunity to human adenoviruses has really made that approach difficult, if not unworkable,” said Christopher Walker of Nationwide Children’s Hospital in Columbus, Ohio, who was not involved in the research. “I think that they have found a very nice way around that.”

Nicosia and his team found their alternative to human adenoviruses from a rather unpleasant source: chimp poop. Because of people’s similarity to chimps, Nicosia reasoned, adenoviruses that can infect chimps can probably infect humans as well. Importantly, however, they generally don’t, so people haven’t built up antibodies to the viruses.